1. Field of the Invention
The present invention relates to a process for obtaining a vanilla flavor by treatment of green vanilla beans, and to the flavor obtained.
2. Description of the Background
The constituents of the vanilla flavor, in particular vanillin, vanillic acid, para-hydroxybenzoic acid and para-hydroxybenzoic aldehyde, are practically absent from the mature green bean at harvesting. The constituents form slowly in the bean after picking.
Normally beans which have been freshly gathered are processed by
(1) heating the beans at 65.degree. C. while they are immersed in water for 3 minutes,
(ii) seasoning during which the beans are placed in boxes lined with wool for 48 h at 30.degree.-40.degree. C., in which they lose their water and take on their brown color,
(iii) drying, in three successive stages, which consists in holding the beans in an oven at 65.degree. C. for 3 hours per day for 7 days, then in exposing them to the sun for 3 to 5 hours per day for 7 days and finally keeping them in the shade, in an airy place, for a month, and lastly,
(iv) a final maturation, which lasts 8 months, in closed chambers,
During the last stage, the state of the beans is monitored each week, and the relatively numerous ones which show mycelial development on the surface are removed, which increases the cost of the treatment.
By this treatment, which is long and which involves numerous manipulations, between 2 and 3 grams of vanillin per 100 g of dry matter in the green beans is obtained, according to the batches of beans and their origin.
In Food Research 8 p. 343-351 (1943), F. E. Arana has indicated that the vanillin formed during the treatment of the beans results from the hydrolysis of a glucoside which is found in the green bean. This glucoside may be extracted from the bean with ethanol, and hydrolyzed either by a .beta.-glucosidase or by an acid in an aqueous medium.
Although in the conventional process there is no more glucovanillin in the treated bean, the quantity of vanillin present at the end of treatment is less than that which could be expected on the basis of the quantity of glucoside present on picking. Accordingly, it should be possible to obtain up to about 5 g of vanillin per 100 g of dry matter, instead of the usual 2 to 3 g. This reduction in the amount of vanillin obtained is likely to be caused by enzymatic or microbial decomposition of the vanillin during its formation, thereby resulting in the formation of vanillic acid in particular. A need therefore exists for a means of obtaining greater yields of vanillin from the vanilla bean.